In recent years, there has been a development of a self-extinguishing cigarette with intent to reduce cigarette-related fires. This self-extinguishing cigarette includes smoking material such as shred tobacco, and paper wrapping the smoking material. The paper is made of a low ignition propensity wrapping paper (for example, see FIG. 2 of Patent Document 1).
To be specific, the low ignition propensity wrapping paper disclosed in Patent Document 1 includes a paper web and bands that are longitudinally arranged in the web at predetermined intervals. These bands are formed by applying a combustion-inhibition liquid onto the web. More specifically, the combustion-inhibiting liquid consists of an aqueous solution and a combustion inhibitor dissolved in this aqueous solution. A web applied with the combustion-inhibiting liquid is dried by a dryer to turn into a low ignition propensity wrapping paper.
A higher concentration of combustion inhibitor in the combustion-inhibiting liquid is better to give a desired low ignition propensity to cigarette paper, or wrapping paper. On the other hand, the higher the concentration of the combustion inhibitor is, the higher the viscosity of the combustion-inhibiting liquid is increased.
High concentration of the combustion-inhibiting liquid makes it difficult to apply the low ignition propensity liquid onto the web, and precludes the accurate band formation on the web. Under the circumstances, it is necessary to reduce the viscosity of the combustion-inhibiting liquid at the time of applying the low ignition propensity liquid onto the web.
The combustion-inhibiting liquid has properties in which its viscosity decreases along with the increase of its temperature. For example, therefore, the combustion-inhibiting liquid may be heated prior to the application of the combustion-inhibiting liquid. Patent Document 1 uses a combustion-inhibiting liquid containing combustion inhibitor of low concentration and repeatedly applies this thin combustion-inhibiting liquid onto web, giving a desired low ignition propensity to wrapping paper (FIG. 4 of Patent Document 1).